α‐Adrenoceptor Assays

Abstract

Important in numerous physiological processes, α-adrenoceptors were among the first receptors identified by use of pharmacological techniques. These receptors are pivotal in controlling cardiovascular function both within the central nervous system and at the periphery, and play major roles in other autonomic functions. In addition, α-adrenoceptors influence the release of other neurotransmitters from synaptic terminals in both the central and peripheral nervous systems. The influence of α-adrenoceptors over autonomic and central nervous system function is thus far reaching. BASIC PROTOCOL 1 EVALUATION OF α 1A -ADRENOCEPTORS IN ISOLATED VAS DEFERENSThis protocol describes the steps required to isolate the rat vas deferens, equilibrate the tissue, and characterize baseline responses to adrenergic compounds. These procedures facilitate study of the pharmacology of responses, either to establish the pharmacological characteristics of the receptors within the tissue or to determine the pharmacological effects of an unknown compound. The latter goal is best achieved using parallel assays for other adrenoceptor subtypes in tissue selectively enriched for those receptors.As with other models employing isolated animal tissues, the tissue must be harvested expeditiously, with oxygenation maintained during preparation and throughout the course of the experiment. Buffered physiological salt solutions continuously bubbled with carbogen (95%O 2 /5% CO 2 ) maintain the correct acid/base balance of the buffer and the oxygen content of the tissue. Aeration also thoroughly mixes test agents in the tissue bath, so that the equilibration time between drug addition and exposure at the receptor sites is rapid.

ALPHA ANTIADRENERGIC EFFECT OF Achyrocline bogotensis EXTRACT (“Vira Vira”) IN ISOLATED RAT AORTIC RING

“…Tamsulosin, for example, an alpha-1a subtype selective antagonist, show greater relaxant potency in isolated rat aortic rings than in isolated rat vas deferens, an experimental model also routinely used to assess this kind of receptor (35). It is interesting, as found in the results of this work, that A. bogotensis displays comparable activity to that seen and described with the reference agent, prazosin (34).…”